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Acceptance Sampling

Acceptance Sampling. By: Cori Rosoff Penn State University OISM 470W. Short Synopsis. Acceptance sampling Defined When is acceptance sampling useful? The risks associated with acceptance sampling. Short Synopsis. Disadvantages of acceptance sampling Application of acceptance sampling

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Acceptance Sampling

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  1. Acceptance Sampling By: Cori Rosoff Penn State University OISM 470W

  2. Short Synopsis • Acceptance sampling Defined • When is acceptance sampling useful? • The risks associated with acceptance sampling

  3. Short Synopsis • Disadvantages of acceptance sampling • Application of acceptance sampling • MoonLight Jeans example

  4. Acceptance Sampling Defined • Acceptance Sampling is a form of inspection that is used to determine whether or not goods are coherent with a set standard of quality

  5. Acceptance Sampling • How can this tool be used in your organization?

  6. When is Acceptance Sampling useful? • When product testing is • destructive • expensive • time consuming • When developing new products

  7. When is Acceptance Sampling useful? • When dealing with new suppliers • When a supplier’s product has had excellent quality in the past

  8. Risks of Acceptance Sampling • Producers Risk • The risk associated with a producer rejecting a lot of materials that actually have good quality • Also referred to as a Type I Error

  9. Risks of Acceptance Sampling • Consumers Risk • The risk associated with a consumer accepting a lot of materials that actually have poor quality • Also referred to as a Type II Error

  10. Acceptance Sampling • Acceptance sampling is a process that helps to determine whether to accept or reject the sample being observed

  11. Disadvantages of acceptance sampling • The process of the goods being inspected is not improved

  12. When can acceptance sampling be applied? • At any point in production • The output of one stage is the input of the next

  13. When can acceptance sampling be applied? • Sampling at the Input stage • Prevents goods that don’t meet standards from entering into the process • This saves rework time and money

  14. When can acceptance sampling be applied? • Sampling at the Output stage • Can reduce the risk of bad quality being passed on from the process to a consumer • This can prevent the loss of prestige, customers, and money

  15. When can acceptance sampling be applied? • Sampling at the Process stage • Can help adjust the process and reduce the amount of poor quality in production • Helps to determine the source of bad production and enables return for reprocessing before any further costs may be incurred

  16. Typical Application of Acceptance Sampling • A vendor delivers a product to a manufacturing company • The product is a raw material used by the company

  17. Typical Application of Acceptance Sampling • A sample of the shipment is taken • Quality characteristics of the units in the sample are inspected.

  18. Typical Application of Acceptance Sampling • Based on the observations made, the decision is made to either accept or reject the entire shipment

  19. Typical Application of Acceptance Sampling • The decision to accept or reject the shipment is based on the following set standards: • Lot size = N • Sample size = n • Acceptance number = c • Defective items = d • If d <= c, accept lot • If d > c, reject lot

  20. Acceptance Sampling Plan • Mr. Smith owns and operates a manufacturing plant. • He receives a shipment of 1,000 sheets of glass. • Of the shipment, Mr. Smith chooses to sample 50 sheets.

  21. Acceptance Sampling Plan • If more than 2 are defective, he is sending back the entire shipment to the supplier. • Mr. Smith observes 5 defective sheets of glass.

  22. Acceptance Sampling Plan • Therefore, according to the set standards mentioned above: • N = 1,000 • n = 50 • c = 2 • d = 5

  23. Acceptance Sampling Plan • What should Mr. Smith do in reference to the number of defective items observed????

  24. Acceptance Sampling Plan • Remember, if d > c, reject lot • Since c = 2, and d = 5… • Mr. Smith should reject the lot of 1,000 sheets of glass

  25. MoonLight Jeans • MoonLight Jeans store receives a shipment of 300 pairs of jeans from its warehouse. • It is common practice for the store to sample 5% of the total received. • The acceptance number under any and all circumstances for MoonLight Jeans is 10.

  26. MoonLight Jeans • Of the 15 pairs of jeans observed, 2 were defective. • What conclusion should the store manager come to based on this information?

  27. MoonLight Jeans • The store manager has just found out that the clerk who inspected the samples made a huge mistake… • The actual number of defective pairs of jeans sampled was 12.

  28. MoonLight Jeans • What type of risk is involved with the error made at MoonLight Jeans? • How might this error affect the store and their customers?

  29. Summary • Acceptance Sampling • a form of inspection that is used to determine whether or not goods are coherent with a set standard of quality • It does not improve the process that the products are derived from

  30. Summary, cont… • Uses of Acceptance Sampling • Risks • Producers Risk • Consumers Risk

  31. Summary, cont… • Stages of Inspection • Input Stage • Process Stage • Output Stage • Example Sampling Plan • MoonLight Jeans Example

  32. Works Cited • Canavos, George C. and Don M. Miller. Custom Edition of Introduction to Business Statistics 2e. USA: Brooks/Cole Publishing Company, 2001. • Foster, S. Thomas. Managing Quality: An Integrative Approach. New Jersey: Prentice-Hall Inc., 2001. • Montgomery, Douglas C. Introduction to Statistical Quality Control. USA: John Wiley & Sons, Inc., 1996.

  33. Works Cited, cont… • Starbird, S. Andrew. “The Effect of Acceptance Sampling and Risk Aversion on the Quality Delivered by Suppliers.” Journal of the Operational Research Society v45 (1994): 309-320. • Wetherill, Barrie G. Sampling Inspection and Quality Control. Great Britain: Butler & Tanner Ltd, 1969.

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